Tune "off" after trans swap?

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Mar 27, 2019 | 06:20 AM

StolenFox

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Tune "off" after trans swap?

I originally built my 6.0L LS swap BMW E39 with a 4L80E that was controlled by a Fast EZ-TCU and had the PCM tuned (04 GTO) locally. Since then I've switched the car over to a manual 6-speed (TR6060) and I'm wondering if the tune needs to be revisited.

Thoughts?

Thanks!
S.F.

Mar 27, 2019 | 10:08 AM

dw456post

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Are you the guy that used to build H pipes?
It sounds like you divorced the PCM from the trans a long time ago. The tune might only change from the different loads in the gearing, but that wouldn't be much, just a little spark and fueling touch up. I'm guessing that you don't have a working speedo?

Mar 27, 2019 | 12:17 PM

StolenFox

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Quote:

Originally Posted by dw456post

Yes, I used to build H-pipes and Axle Backs for the 04-06 GTO and the 08-09 G8's. You are correct in that the PCM does not care about the trans and hasn't since day-1 but I am curious about the gearing differences causing a less than ideal tune. 4L80E and TR6060 ratios are quite a bit different if I recall correctly.... Speedo is working fine as its driven off the rear half-shaft (BMW's are weird) and the TR6060 is sending the speed signal to the PCM.

Thanks!
S.F.

Mar 27, 2019 | 12:37 PM

G Atsma

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From: Central Cal.

If an engine is tuned correctly for all circumstances, it should run correctly no matter what. The only time an engine should need tuning for a different setup is if/when some parts of the A/F table(s) aren't correctly populated, if indeed they are populated.